CCNP Practice Test 12 — 15 Questions

Question 1

Refer to the exhibit. A network administrator notices that some DHCP packets are being dropped due to 'MAC Address Mismatch'. What is the most likely cause of this drop?

Accepted Answer

The DHCP client is using a different MAC address in the DHCP packet than the source MAC in the Ethernet frame.. The DHCP snooping feature on a switch compares the source MAC address in the Ethernet frame with the chaddr (client hardware address) field inside the DHCP packet. When a DHCP client sends a packet with a different MAC in the frame than in the chaddr field, the switch considers it a 'MAC Address Mismatch' and drops the packet. This security mechanism prevents a rogue client from spoofing another device's MAC address to obtain a lease.

Answer

The DHCP server is sending packets with an incorrect server identifier option.

Answer

The DHCP client is sending a request with an incorrect transaction ID.

Answer

The DHCP offer packet is arriving on an untrusted port.

Question 2

A network engineer is automating the deployment of VLANs across multiple switches using Ansible. The playbook runs successfully on most switches, but one switch fails with an error indicating that the VLAN configuration command is not recognized. What is the most likely cause?

Accepted Answer

The switch runs a different IOS version with different VLAN CLI syntax. The most likely cause is that the switch runs a different IOS version with different VLAN CLI syntax. Ansible executes commands via SSH, and if the switch expects a different command format (e.g., 'vlan 10' vs. 'vlan database' on older CatOS), the playbook will fail with a command-not-recognized error. This is a common issue when automating across heterogeneous network devices.

Answer

Ansible lacks the appropriate module for VLAN configuration

Answer

The inventory file has a syntax error for that specific host

Answer

SSH connectivity to the switch is blocked by an ACL

Question 3

A DevOps team is implementing a CI/CD pipeline that automates network configuration changes. Which design principle is most important to ensure that a failed deployment does not cause prolonged outages?

Accepted Answer

Ensure the automation framework supports rollback to a known good state. Option B is correct because in a CI/CD pipeline for network automation, the ability to roll back to a known good state is the most critical design principle for minimizing downtime. If a deployment fails (e.g., a misapplied ACL or BGP configuration), the automation framework must be able to revert the network device to its previous stable configuration—often by reapplying a saved startup config or using a tool like Ansible's `network_backup` role or Cisco NSO's rollback mechanism. Without this, a failed deployment could leave the network in a broken state until manual intervention, causing prolonged outages.

Answer

Use a single source of truth for all configurations

Answer

Implement idempotent configuration scripts

Answer

Run the deployment in a lab environment first

Question 4

A network engineer is troubleshooting an automated configuration change that caused a routing loop. The change was pushed via an Ansible playbook that modified OSPF cost values on multiple routers simultaneously. What is the most likely reason for the loop?

Accepted Answer

The changes were applied simultaneously without allowing OSPF to converge between updates. Option C is correct because applying OSPF cost changes simultaneously on multiple routers without allowing convergence between updates can cause transient routing loops. OSPF relies on the SPF algorithm to calculate loop-free paths based on consistent link-state databases across the network. When costs are changed on multiple routers at once, some routers may have outdated LSAs, leading to inconsistent forwarding tables and temporary loops until all routers reconverge.

Answer

OSPF does not support changing costs on multiple routers at the same time

Answer

OSPF uses hop count as a metric, and the changes caused a count-to-infinity issue

Answer

The OSPF cost values were changed to non-standard values that OSPF cannot process

Question 5

A network engineer runs the following command on Switch SW2:

SW2# show spanning-tree vlan 20

VLAN0020
  Spanning tree enabled protocol ieee
  Root ID    Priority    24596
             Address     aabb.cc00.0200
             Cost        4
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32778  (priority 32768 sys-id-ext 20)
             Address     aabb.cc00.0300
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 4         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Altn BLK 4         128.3    P2p

Based on this output, what can be concluded?

Accepted Answer

GigabitEthernet0/3 is in the Blocking state to prevent a loop.. SW2 is not the root bridge (its bridge priority 32778 is higher than root priority 24596). Gi0/1 is the root port (cost 4 to root), Gi0/2 is a designated port, and Gi0/3 is an alternate port in blocking state. The root bridge is at MAC aabb.cc00.0200.

Answer

SW2 is the root bridge for VLAN 20.

Answer

The root port cost is 8.

Answer

SW2's bridge priority is 32768.

Question 6

A network engineer runs the following command on Switch SW5:

SW5# show spanning-tree vlan 50

VLAN0050
  Spanning tree enabled protocol ieee
  Root ID    Priority    24626
             Address     aabb.cc00.0800
             Cost        4
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 50)
             Address     aabb.cc00.0900
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 4         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Desg FWD 4         128.3    P2p
Gi0/4               Altn BLK 4         128.4    P2p

Based on this output, how many ports are in the Forwarding state?

Accepted Answer

3. The output shows three ports in Forwarding state: Gi0/1 (Root FWD), Gi0/2 (Desg FWD), and Gi0/3 (Desg FWD). Gi0/4 is in Blocking state (Altn BLK).

Answer

1

Answer

2

Answer

4

Question 7

A network engineer runs the following command on Switch SW3:

SW3# show spanning-tree vlan 30

VLAN0030
  Spanning tree enabled protocol ieee
  Root ID    Priority    24606
             Address     aabb.cc00.0400
             Cost        12
             Port        2 (GigabitEthernet0/2)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32798  (priority 32768 sys-id-ext 30)
             Address     aabb.cc00.0500
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Desg FWD 4         128.1    P2p
Gi0/2               Root FWD 12        128.2    P2p
Gi0/3               Desg FWD 4         128.3    P2p

Based on this output, what is the root path cost from SW3 to the root bridge for VLAN 30?

Accepted Answer

12. The root path cost is the cost of the path from this switch to the root bridge. It is shown in the Root ID section as 'Cost 12'. This is the cumulative cost via the root port (Gi0/2, which has a cost of 12).

Answer

4

Answer

16

Answer

20

Question 8

A network engineer runs the following command on Switch SW6:

SW6# show spanning-tree vlan 60

VLAN0060
  Spanning tree enabled protocol ieee
  Root ID    Priority    24636
             Address     aabb.cc00.0a00
             Cost        8
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 60)
             Address     aabb.cc00.0b00
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 8         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Altn BLK 4         128.3    P2p
Gi0/4               Desg FWD 4         128.4    P2p

Based on this output, what is the bridge priority of the root bridge for VLAN 60?

Accepted Answer

24636. The root bridge priority is shown in the Root ID section as 24636. This includes the system ID extension of 60, so the base priority is 24576 (24636 - 60 = 24576).

Answer

24576

Answer

32768

Answer

32828

Question 9

A network engineer runs the following command on Switch SW4:

SW4# show spanning-tree vlan 40

VLAN0040
  Spanning tree enabled protocol ieee
  Root ID    Priority    24616
             Address     aabb.cc00.0600
             Cost        8
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 40)
             Address     aabb.cc00.0700
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 8         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Desg FWD 4         128.3    P2p

Based on this output, which port is the root port?

Accepted Answer

GigabitEthernet0/1. The root port is the port that provides the best path to the root bridge. In the output, Gi0/1 is listed as 'Root FWD', indicating it is the root port.

Answer

GigabitEthernet0/2

Answer

GigabitEthernet0/3

Answer

There is no root port because SW4 is the root bridge.

Question 10

A network engineer runs the following command on Switch SW7:

SW7# show spanning-tree vlan 70

VLAN0070
  Spanning tree enabled protocol ieee
  Root ID    Priority    24646
             Address     aabb.cc00.0c00
             Cost        4
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 70)
             Address     aabb.cc00.0d00
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 4         128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Altn BLK 4         128.3    P2p

Based on this output, which port is the alternate port?

Accepted Answer

GigabitEthernet0/3. The alternate port is the port that provides an alternative path to the root bridge and is placed in blocking state. In the output, Gi0/3 is shown as 'Altn BLK'.

Answer

GigabitEthernet0/1

Answer

GigabitEthernet0/2

Answer

There is no alternate port.

Question 11

interface GigabitEthernet0/1
 spanning-tree portfast
 spanning-tree bpduguard enable
 end

What is the effect of this configuration?

Accepted Answer

The port will immediately transition to forwarding state and will be error-disabled if a BPDU is received.. PortFast and BPDU Guard are enabled on the interface, which immediately transitions the port to forwarding and disables it if a BPDU is received.

Answer

The port will go through normal STP states and will be error-disabled if a BPDU is received.

Answer

The port will immediately transition to forwarding and ignore any BPDUs received.

Answer

The port will remain in blocking state until a BPDU is received.

Question 12

interface GigabitEthernet0/3
 spanning-tree guard root
 end

What is the effect of this configuration?

Accepted Answer

The port will error-disable if it receives a BPDU that would cause the switch to become a non-root bridge.. Root Guard is enabled on the port, which will error-disable the port if a superior BPDU (indicating a potential root bridge) is received.

Answer

The port will block all BPDUs received from other switches.

Answer

The port will become the root port for the VLAN.

Answer

The port will ignore BPDUs from switches with lower bridge ID.

Question 13

What is the default STP hello timer value in seconds?

Accepted Answer

2 seconds. The default hello timer in STP is 2 seconds, used to send BPDUs on the root bridge.

Answer

1 second

Answer

5 seconds

Answer

10 seconds

Question 14

A network engineer runs the following command on Switch SW8:

SW8# show spanning-tree vlan 80

VLAN0080
  Spanning tree enabled protocol ieee
  Root ID    Priority    24656
             Address     aabb.cc00.0e00
             Cost        12
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32768  (priority 32768 sys-id-ext 80)
             Address     aabb.cc00.0f00
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/1               Root FWD 12        128.1    P2p
Gi0/2               Desg FWD 4         128.2    P2p
Gi0/3               Desg FWD 4         128.3    P2p
Gi0/4               Altn BLK 4         128.4    P2p

Based on this output, what is the cost of the root port?

Accepted Answer

12. The root port is Gi0/1, and its cost is shown as 12 in the interface table.

Answer

4

Answer

8

Answer

16

Question 15

spanning-tree vlan 10 priority 4096

What is the effect of this global configuration command?

Accepted Answer

The switch will have a bridge priority of 4096 for VLAN 10, increasing its chance to become root bridge.. This sets the bridge priority for VLAN 10 to 4096, making the switch more likely to become the root bridge for that VLAN.

Answer

The switch will have a bridge priority of 4096 for all VLANs.

Answer

The switch will become the root bridge for VLAN 10 immediately.

Answer

The switch will have a bridge priority of 4096 for VLAN 10 and all other VLANs will use 32768.

CCNP Practice Test 12 — 15 Questions

Exhibit

CCNP Practice Test 12 — 15 Questions

Exhibit